Validate incoming message in xml default pipeline

1) Open BizTalk Server Administration Console
2) Click on the application contain the receive location
3) Click on “Receive Locations”
4) Double click the particular receive location on the right hand side
5) Click the button next to the drop down list entitled “Receive pipeline”
6) Change “ValidateDocument” to true
7) set the DocumentSpecName
You can get the DocumentSpecName of a schema information by clicking on the schema node inside the
biztalk application by doing the Combination of Name + “,” + Assembly

Biztalk orchestration patterns

http://patternwizard.codeplex.com/

Grouping in xslt

http://blogs.msdn.com/b/chrisromp/archive/2008/07/31/muenchian-grouping-and-sorting-in-biztalk-maps.aspx
http://blogs.msdn.com/b/skaufman/archive/2005/12/19/505654.aspx

for multilevel grouping concate the fields to create unique key like here
http://www.biglist.com/lists/xsl-list/archives/200101/msg00070.html

while creating keys in xsl, if you want to create keys based on some filed value, use like below

 <xsl:key name="UniquePhoneHomeGroups" match="HorizonEdExtract[PhoneHome/text() != '']" use="concat(ID,PhoneHome)"/>

the above key matches againt all non empty PhoneHome nodes under HorizonEdExtract record.
if you want compare attribute of a node you can use below

<xsl:key name="bookByLanguage" match="book[@isenglish="Yes"]" use="id"/>
or you can use multiple conditions like below 
<xsl:key name="booksEnglishNoPub" match="book[@isenglish='Yes' and @pub-id='']" use="id"/>
(This multiple condition is not tested)

http://p2p.wrox.com/xslt/66290-giving-two-conditions-match-xsl-key.html